This process of using similar recognised shapes to align two scans together. This process is a fast and simple process for connecting scans together and used in cases where there is no other information to register. Registration can be done using planes where faces are taken into consideration or manually where common areas are identified in different scans to register against.
Small differences can occur in this registration process as it uses flat vertical surfaces to register with. It can be difficult to achieve survey grade accuracies outdoors through this process alone.
Cloud Based Registration looks at the two clouds and uses only algorithms to best fit the scans together. Cloud based registration is impacted by the data within a point cloud and relies heavily on flat vertical faces to be present in the scans for registration.
Tress (forest/bush) and poles do not make great vertical data for registration as they change depending on the angle being scanned.
Below are three examples of the registration process. The top example is a large flat area which will have more trouble registering than the bottom example with lots of vertical surfaces.
Any errors that are introduced in the registration process will propagate through the length of the project. So, the longer a set of scans are joined together in one group, the further and more impact errors will impact on results.
While the process relies heavily on flat vertical faces to be existing in the scans for registration, it isn’t to say areas without this can’t be used, it just makes registration more difficult.
When in doubt and there are issues with registration, add another scan in.